Drafting triangle



Sept. 7,1926. 1,598,690

J. A. PETRONIO 'DRAF'IING TRIANGLE;

Filed Oct. 25, 1924 JED .2.

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JEROME A. PETRONIO, OF NEW YORK, N. Y.

DRAIETING TRIANGLE.

Application filed October 28, 1924. Serial No. 745,442.

This invention relates to improvements in drafting instruments and more particularly to a novel triangle which may be employed with great advantage by draftsmen, engineers, artists, and all who are interested in drafting and the reading of drawings.

One of the objects of the present invention is to provide a triangle embodying features which will permit of its use, alone,

10 under conditions where it has heretofore been customary to employ simultaneously, two triangles, thereby, by the use of the instrument of the present invention, avoiding confusion and errors and effecting a considerable saving in time.

Another object of the invention is to provide a triangle which will be useful in many ways where an ordinary triangle could not be successfully employed.

In the accompanying drawings:

Figure 1 is a plan view ofthe triangle embodying the, invention.

Figure 2 is a sectional view therethrough, taken substantially on the line 22 of Figure 1, looking in the direction indicated by the arrows. 4

The instrument embodying the invention is primarily a 30 triangle and comprises a body 1 which is of clear, transparent celluloid or other material found suitable for the purpose, the right angle straight edges of the triangle being indicated, one by the numeral 2 and the other by the numeral 3, and the diagonal straight edge being indicated by the numeral 4. The upper side of the body of the triangle is beveled along the straight edge 3 in amanner to permit a pencil or ruling pen to draw a straight sharp line and bears a linear scale indicated by the numeral 5, the divisions of which, in the illustrated embodiment of the invention, represent inches and fractions of inches. On a 45.line between the straight edges 2 and 3 and opposite the point of juncture of these edges, the body of the triangle is formed with an opening 6, and lines 7 and 8 are impressed in the upper face of the body of the triangle parallel to the straight edges 2 and 3 and consequently at right angles to each other, the lines meeting at the o ening 6. Slots 9 of arcuate form are provi ed in the body of the triangle concentric to the opening 6, and extend from the lines 7 and 8h to t ey are separated at their relatively adjacent respectively,

ends by a portion 10 of the triangle which is left intact in order to reinforce the instrument at this point. The upper side of the instrument is beveled as at 11, atopposite sides of the slot 9, and protractor scales 12 are impressed upon the face of the instrument at the beveled surfaces 11, a second opening 13 being preferably formed in the triangle in alinement with the reinforcing portion 10 and consequently on a line intersecting the 45 mark of the protractor scales and the opening 6. The openings 6 and 13 are, of course, provided for the insertion of a pencil point or a needle point, as is usual in instruments of this class. The triangle is formed within the boundary of the lines 7 and'8 and the protractor scales,

with an opening'li which is of triangular form, the edges of the body of the instrument defining or bounding the opening, forming a 45 triangle.

The body of the instrument is further formed with a triangular opening 15, one side 16 of which is parallel to the edge 2 of the instrument and another side 17 parallel to the straight edge 3 of the triangle, the other side of the opening, indicated by the numeral 18, being oblique to the sides 16 and 17 and the walls of the opening defining a 15 triangle. The opening 15 is located relatively close to scale 5 and immediately above one end of the protractor scale 12, and a slot 19 is formed in the body of the instrument between the opening 15 and the oblique straight edge l of the instrument, the walls of this slot being at an angle of 22 to the straight edge 3 of the instrument.

From theforegoing description of the in vention, it will be evident that one using the instrument has at his command a 30 triangle, a 415 triangle, a 15 triangle, and the slot 19 which is disposed at an angle of 22 Therefore, the plotting of angles and the division of circles and arcs of circles into predetermined numbers of parts or divisions, may be readily accomplished. It will also be understood from the foregoing and from the drawing, that whereas heretofore it has been absolutely necessary to employ a 30 triangle and a 45 trian le in conjunction with each other, in dividing a circle into twenty-four parts, the 15 an 1e provided by the opening 15 in body of t e instrument of the present invention, permits the linear ofsuch division of a circle without the difficulty heretofore experienced in adjusting the two first mentioned triangles.

. protractor or compass.

' ent Itis a well known fact that a triangle is recognized as one in which the hypotenuse is at an angle of 45 to the perpendicular straight edge of the instrument; that a 30 triangle is recognized as one in which the hypotenuse is at an angle of 30 to the perpendicular straight edge of the instrument, etc., and it may, therefore, be said that this angular distance between the hypotenuse and the perpendicular straight edge of the differinstruments determines the an ular value of atriangle, and this term will be so employed in the appended claims.

In addition to the triangular space 14 formed in the body of the instrument there is provided a slot 20 which extends parallel to the diagonal wall of the said opening 14 and, therefore, at an angle of 45 to the base edge 2 of the body of the instrument and the straight edge 3 thereof.

Having thus described the invention, what I claim is:

1. A drafting instrument consisting of a right angled triangle havin a 45 triangular opening with two sides of the opening parallel with the two sides of the triangle, and having an arcuate slot between the triangular opening and the hypotenuse of the triangle, formed on a circle whose center lies on the other side of the said triangular opening on a line perpendicular to the hypotenuse thereof and passing through the point of intersection of the said two sides of the opening.

2. A drafting instrument consisting of a right angled triangle having a 45 trian ular opening with two sides of the opening parallel with the two sides of the triangle, and having an arcuate slot between the triangular opening and the hypotenuse of the triangle, and having a slot intermediate the triangular opening and the arcuate slot parallel-ing the hypotenuse of the triangular opening.

3. A drafting right angled triangle having a punch opening ad'acent the angle formed between the two si es and a punch opening adjacent the hypotenuse, the two punch openin being on a 45 angle with respect to eit er side and having arcuate slots concentric with the punch opening adjacent the side and formed on a circle having a common radius, said A slots terminating at their adjacent ends upon opposite sides of the said 45 angle defined by .the two punch openings. j 4. A drafting instrument consisting of a 30 right angled triangle having a 45 triangular openin in the angle formed between the two sldes, corres onding sides of the triangle and opening eing parallel, a 15 triangular opening in the angle formed between the hypotenuse and a side of the triangle, with correspondin sides of the triangle and the 15 triangu ar opening arallel, and having arcuate slots opposite t e 45 triangular opening and havin straight slots adjacent and extendin in substantially the same direction as the ypotenuse of the respective two triangular openings, the arcuate slots having protractor scales at opposite sides. I

In testimony whereof I aflix my signature.

JEROME A. PETRONIO. [L. 5.]

instrument consisting of a 

